Process of making manure from tanned-leather shavings or cuttings.



ALFRED MOISE, OF BARR, GERMANY.

PROCESS OLE MAKING MANURE FROM TANNED-LEATHER SHAVINGS OR CUTTINGS.

No Drawing.

To all whom it may concern Be it known that I, ALFRED Morse, a citizen of the German Empire, and residing at Barr, Alsace, Germany, have invented a certain new and useful Improved Process of Making Manure from Tanned-Leather Shavings or Cuttings, of which the following is a specification.

My invention relates ing a valuable manure from tanned, leather shavings or cuttings, while simultaneously recovering the greater part of the tannin in the shavings and thus rendering the process in every way a very lucrative one.

Many attempts have already been made to utilize tanned leather shavings for agricultural purposes. Here however difliculties have been met with, since when in the ground such leather refuse is only very slowly decomposed because the tannin in the leather tends to prevent such decomposition. The result is that leather refuse has so far only acted as a very poor nitrogenous manure. In order to better utilize such leather refuse it has been found necessary to subject it to a preliminary treatment principally consisting in first disaggregating the leather refuse, 2'. 0. opening up the cells of the same, by a lengthy application of high pressure steam, and then finely triturating the product. Moreover, the leather refuse has also been treated with the alkaline carbonates or with acids, 6. g.'sulfuric acid. The principal object in employing an acid or alkali has been to destroy the tannin in the leather refuse, because such tannin militates against the decomposition of the leather when in the ground, and will often prolong such decomposition for years. Such processes are of course not very profitable because a valuable material such as the tannin becomes thereby destroyed instead of being recovered in such a form that it can be reemployed for tanning further hides.

A primary object of my invention is to obviate the above defects and not only to obtain from leather refuse a valuable artificial manure rich in nitrogen, but to extract from such refuse almost thewhole of the useful tannin and obtain it in such a form that it can be used again. At the same time owing to the extraction of the tannin, the resulting product serves as a readily decomposable manure.

The process according to my invention essentially consists 1n first lixiviating the to a process of mak- Specification of Letters Patent.

Patented Mar. 31., 1914.

Application filed October 30, 1912. Serial No. 728,744.

finely subdivided leather refuse with water, at a temperature of about 50 to 0., and in then treating the lixiviated product in accordance with a known disaggregating process. Owing to the removal of the tannin, however, this disaggregation process can be carried out in considerably less time and with relatively smaller quantities of chemicals than have been usually necessary, and consequently both work and expense are saved. The further advantage is also obtained that the leach resulting from the llX- iviation of the leather refuse at the stated moderate temperature contains a tannin which, because almost unaltered in composi tion, can again be utilized as a valuable tanning agent. It should further be stated that, owing to the removal of the tannin, the manure obtained is not only readily deco-mposable, but contains a greater percentage both of nitrogen and phosphorus.

The following is one example of the manner in which my process can be carried out :-The tanned leather cuttings or shavings after being finely subdivided are mixed with water in an extraction-battery. Heat is then applied, care being taken that the material does not come into contact with the hot steam, because otherwise, owing to the glue contained in the leather refuse, the latter would immediately clog the sieves in the extractor. The steam is admitted until the mass to be lixiviated has reached a temperature of about 50 to 60 C. Lixiviation is then continued by continually stirring around the contents to prevent the formation of lumps, until the leather refuse has yielded practically all its tannin, this being easily ascertained by treating the lixiviating liquid with an approximately 10% ferric chlorid solution when little or no change in coloration should be obtained.

When a closed extractor is employed, it is better after extraction to subject the extractor to two atmospheres air-pressure and so better press out the remaining liquid.

The leach can be concentrated to any desired strength by suitable evaporation, and then yields an excellent tannin. It is possible in this manner to obtain as much as 20% tannin from the leather refuse, and it is evident that the percentage of nitrogen and phosphorus in the remaining refuse will consequently be considerably greater.

I have also found that when greasy leather cuttings are employed it is preferable to treat them with benzin or other fatsolvents before leaching out the tannin. By doing this I not only obtain a useful fat, for leather cuttings contain on an average 10% fat, but, owing to this fat being extracted I obtain the tannin in aconsiderably purer form as the result of the lixiviation with about 100 C. I have also found that this.

disaggregation process when applied after the said lixiviation of the soluble tannin can be carried out in considerably less time than when applied in the usual manner. In some cases, half the time and half the material for the disaggregation process are saved. The

1 product thus obtained may finally be dried and triturated or ground to powder in a suitable manner.

According to the above-described process I therefore obtain firstlyQthe fat from the leather, secondly, a valuable tannin, amounting to from 10 to 20% of the leather refuse, and finally an exceedingly useful manure having percentages of nitrogen and phosphorus which, as compared with such percentages in the starting material 2'. e. the ordinary leather shavings, have been increased by 2 to 3%. Moreover both the work and expense required in obtaining the final re sult are considerably less than in hitherto known processes.

To decompose leather scraps with sulfuric acid is already known, but leather so decomposed by acid is very objectionable for the reason that, upon drying, it develops very unhealthy and disagreeable odors, and when it is packed in bags, after having been dried, it agglomerates into lumps in wet weather or when stored in damp places. Leather disaggregated with alkali such, for example, as soda, does not agglomerate into lumps and, moreover, the alkali treatment of the leather scraps has the further advantage over the acid treatment of avoiding or reducing the tendency to attack or destroy the vessels or receptacles employed in carrying out the process.

2. A process of producing manure from leather refuse of the character described,

refuse, then removing the grease therefrom by treating with suitable fat solvents, then lixiviating the remaining mass with water at 50 to 60 centigrade until the tannin has been practically removed therefrom, then disaggregating the mass remaining by the application of high temperature steam and of an alkali, and finally" drying and triturating this disaggregated material.

3. A process of'producing manure from leather refuse ofthe character described, comprising first finely subdividing the said refuse, then'lixiviating the product with comprising first finely subdividing the said water at 50 to 60 centigrade until the tan nin has been practically removed therefrom, then removing the remaining liquid from the mass, disaggregating the mass remaining by the application of high temperature steam and of an alkali, and finally drying and triturating this disaggregated material.

4. A process of producing manure from leather refuse of the character described, comprising first finely subdividingthe said refuse, then lixiviating the product with water at 50 to 60 centigrade until the tannin has been practically removed therefrom, then applying excess air pressure in such manner as to remove the remaining liquid from the mass, disaggregating the mass re maining by the application of high temperature steam and of an alkali, and finally drying and triturating this disaggregated material.

In testimony whereof, I affix my signature in the presence of two witnesses.

ALFRED MOISE.

Witnesses AUGUST OOSTERMAN, JAooB SCHMIDT.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

